A load adjustment device has a throttle valve (9) which determines the output of an internal combustion engine and is attached, fixed for rotation, to a throttle-valve shaft (36) arranged in the throttle-valve housing. The load adjustment device includes a setting element which cooperates with a driver (4) coupled to an accelerator pedal (1), the pedal acting on the throttle-valve shaft. The setting element is adapted for control by an electric motor (14) which cooperates with an electronic regulating device (17), the motor being adapted for connection to the throttle-valve shaft (36) by a first driver (45) which acts in a single direction.
In load adjustment devices which cooperate with carburetors or injection pumps, optimal control of the internal combustion engine over the entire range of loads is necessary. For this purpose, complicated construction or complicated control is necessary. Thus, carburetors, for instance, in addition to the actual means for forming the mixture have additional devices such as leaning, starting, idling, accelerating and economizing devices, etc. These means complicate the construction of the carburetor and result in a high expense for structural parts, in that additional injection nozzles, pumps, special developments of the nozzle needles, and separate air feeds are necessary, entirely aside from the extensive control requirements connected therewith.
It is particularly important in load adjustment devices to control the state of the idling load, at which only minimum power is given off by the internal combustion engines which however, under certain circumstances and particularly in motor vehicles, must cover load-consuming devices which require extensive power, such as fans, rear-window heating, air conditioning, etc. In order to take these possible power requirements into account, control of the load adjustment device between a minimum idle position and a maximum idle position is necessary. In the event of failure of the control, an emergency idle position of the setting member or control member must be assured.
Differing from the problem described above, load adjustment devices of the type indicated are used, in general, in cases in which the accelerator pedal and the setting member are electronically connected to each other. The accelerator pedal is coupled to the driver and the latter is coupled to the control element. Furthermore, a desiredvalue detection element which is associated with the driver and an actual-value detection element which cooperates with said desired-value detection element and acts on an electric setting drive are provided, the electric setting drive being adapted to be controlled by an electronic control means as a function of the values detected.
The electric connection of accelerator pedal and setting member with the electronic control means interposed between them makes it possible: (1) to set desired-value positions pre-determined by the accelerator pedal and the driver connected to it with reference to the actual values indicated by the position of the control element and of the setting member, and (2) to check them for the existence or absence of plausibility conditions. Thereby, if certain plausibility conditions are present or absent, the possibility exists of acting, via the electronic control means, by control of the electric setting drive on the setting member in order to correct it. The electric setting drive may be developed, for instance, as throttle valve or injection pump.
Thus, for instance, action by the electronic control means can be provided in order to avoid wheel slippage when starting as a result of the establishing of excessive power by way of the gas pedal. Other automatic actions on the load adjustment device are, for instance, conceivable in connection with the automatic shifting processes of a transmission, a speed-limiting control or the above-mentioned idling control of the internal combustion engine.